The present invention relates to an aromatic monomer-metal complex, an aromatic polymer-metal complex, which can be prepared from the monomer-metal complex, and an organic electronic device that contains a film of the polymer-metal complex.
Organic electronic devices are found in a variety of electronic equipment. In such devices, an organic active layer is sandwiched between two electrical contact layers; the active layer emits light upon application of a voltage bias across the contact layers.
Polymers containing pendant metal-complex groups constitute a class of polymers suitable for light emitting applications, particularly in active matrix driven polymeric LED displays. These polymers can be prepared, for example, by first polymerizing a monomer containing a ligand capable of complexing with a metal, then contacting the polymer with an organometallic complexing compound to insert the metal center into the polymer bound ligand. For example, in Macromolecules, Vol. 35, No. 19, 2002, Pei et al. describes a conjugated polymer with pendant bipyridyl groups directly coordinating with various Eu+3α,β-diketones.
Similarly, in WO 02/31896, pp 17-18, Periyasamy et al. describes lanthanide metal-complexed polymers prepared by either a one- or two-step synthetic route. In the one-step route, an MLn emitter is reacted with a polymer having metal-reactive functionality (X) to form a polymer with pendant —X-MLn-1 groups. In the two-step route, a polymer with pendant hydroxyethyl functionality is first condensed with a bipyridyl compound containing carboxylic acid functionality to form a polymer containing bipyridyl ester functionality (X-L′), which is then reacted with MLn to form a polymer with pendant X-L′-MLn-1 functionality.
One of the problems with these metal complexed electroluminescent polymers is the incomplete reaction of pendant ligands with the metal complexing reagent. This inefficient coupling results in unpredictability of the properties of the final polymer due to the difficulty in controlling the degree of metal-ligand complexation. Accordingly, it would be advantageous to prepare a luminescent polymer with precisely controlled metal complexation.